Oil pressure and temperature sensor
The oil pressure and temperature sensor in the clutch unit are close to the axial solenoid in the housing for the differential control module (DEM). The sensor is flushed with hydraulic fluid. The sensor gauges the temperature and pressure of the hydraulic fluid (measurement range 0-4 MPa). The sensor transmits signals about temperature and pressure to the control module. The control module uses the temperature and pressure signals to adapt the function of the system, changing the temperature, and therefore the viscosity, of the fluid as required.
If the temperature of the fluid exceeds 100 °C there is no pressure in the coupling and all wheel drive is disengaged. When the temperature falls below 100 °C the coupling is pressurized again. If the oil pressure exceeds 7.4 MPa, the safety valve in the coupling opens. The coupling is pressurized again when the oil pressure drops below 7.4 MPa.
Four wheel drive is not available if there is a fault in the pressure and/or temperature sensor.
There are diagnostics for the oil pressure and temperature sensor.